@Armin Etemadi, this forum is not dead. Only thing is this feature was never on high priority. There are many features that are suggested by user but not implemented, it is because of time and importance.

Look at the current version of Q2A and see how many features it support. Also pls dont forget it is free software supported by ONLY Q2A passionate people.

No need for registration. Once you click LOGIN, it will automatically log you in. Of course for security reasons on that site, Private Message and Wall Posts are not supported in Q2A SSO. But this editor has been tested on all these areas.

What is the version of your "latest q2a" ?
This editor was designed for 1.7.4 . unless something mysterious has broken, that version on Github works perfectly as attested by @arjunsuresh